Application of a Multiaxial Load-Notch Strain Approximation Procedure to Autofrettage of Pressurized Components

Theoretical approaches to predict the effect of autofrettage on the formation of residual stresses have been limited to tubes. This paper presents a new procedure to calculate approximately the residual stresses in pressurized components of any shape—with and without notches. The procedure developed can account very precisely for changes in the deformation behavior of metals during the first load cycles, e.g. the Bauschinger effect. An extension of the constitutive model of Mróz to cyclic hardening and softening was developed to verify the approximation with finite element analyses. Very good agreement between the results of both approaches was found. Through application of the procedure it was found that maximum residual stresses were usually generated by the pressure, producing a fully plastic net section. Only in a special case did the pressure, which gave maximum residual stresses, coincide with the lowest pressure, producing reversed yielding, which in the past often has been regarded as optimal pressure.